Bug 1605119 - Add NS_NewCancelableRunnableFunction. r=froydnj

Differential Revision: https://phabricator.services.mozilla.com/D57799

--HG--
extra : moz-landing-system : lando

xpcom/tests/gtest/TestThreadUtils.cpp

@@ -5,6 +5,7 @@
 #include "nsComponentManagerUtils.h"
 #include "nsThreadUtils.h"
 #include "mozilla/IdleTaskRunner.h"
+#include "mozilla/RefCounted.h"
 #include "mozilla/UniquePtr.h"
 
 #include "gtest/gtest.h"
@@ -186,6 +187,10 @@ struct TestCopyMove {
   int* mMoveCounter;
 };
 
+struct TestRefCounted : RefCounted<TestRefCounted> {
+  MOZ_DECLARE_REFCOUNTED_TYPENAME(TestRefCounted);
+};
+
 static void Expect(const char* aContext, int aCounter, int aMaxExpected) {
   EXPECT_LE(aCounter, aMaxExpected) << aContext;
 }
@@ -198,24 +203,44 @@ static void ExpectRunnableName(Runnable* aRunnable, const char* aExpectedName) {
 #endif
 }
 
-static void TestNewRunnableFunction(bool aNamed) {
-  // Test NS_NewRunnableFunction with copyable-only function object.
+struct BasicRunnableFactory {
+  static constexpr bool SupportsCopyWithDeletedMove = true;
+
+  template <typename Function>
+  static auto Create(const char* aName, Function&& aFunc) {
+    return NS_NewRunnableFunction(aName, std::forward<Function>(aFunc));
+  }
+};
+
+struct CancelableRunnableFactory {
+  static constexpr bool SupportsCopyWithDeletedMove = false;
+
+  template <typename Function>
+  static auto Create(const char* aName, Function&& aFunc) {
+    return NS_NewCancelableRunnableFunction(aName,
+                                            std::forward<Function>(aFunc));
+  }
+};
+
+template <typename RunnableFactory>
+static void TestRunnableFactory(bool aNamed) {
+  // Test RunnableFactory with copyable-only function object.
   {
     int copyCounter = 0;
     {
       nsCOMPtr<nsIRunnable> trackedRunnable;
       {
         TestCopyWithNoMove tracker(&copyCounter);
-        trackedRunnable =
-            aNamed ? NS_NewRunnableFunction("unused", tracker)
-                   : NS_NewRunnableFunction("TestNewRunnableFunction", tracker);
+        trackedRunnable = aNamed ? RunnableFactory::Create("unused", tracker)
+                                 : RunnableFactory::Create(
+                                       "TestNewRunnableFunction", tracker);
         // Original 'tracker' is destroyed here.
       }
       // Verify that the runnable contains a non-destroyed function object.
       trackedRunnable->Run();
     }
     Expect(
-        "NS_NewRunnableFunction with copyable-only (and no move) function, "
+        "RunnableFactory with copyable-only (and no move) function, "
         "copies",
         copyCounter, 1);
   }
@@ -227,37 +252,37 @@ static void TestNewRunnableFunction(bool aNamed) {
         // Passing as rvalue, but using copy.
         // (TestCopyWithDeletedMove wouldn't allow this.)
         trackedRunnable =
-            aNamed ? NS_NewRunnableFunction("unused",
+            aNamed ? RunnableFactory::Create("unused",
                                              TestCopyWithNoMove(&copyCounter))
-                   : NS_NewRunnableFunction("TestNewRunnableFunction",
+                   : RunnableFactory::Create("TestNewRunnableFunction",
                                              TestCopyWithNoMove(&copyCounter));
       }
       trackedRunnable->Run();
     }
     Expect(
-        "NS_NewRunnableFunction with copyable-only (and no move) function "
+        "RunnableFactory with copyable-only (and no move) function "
         "rvalue, copies",
         copyCounter, 1);
   }
-  {
+  if constexpr (RunnableFactory::SupportsCopyWithDeletedMove) {
     int copyCounter = 0;
     {
       nsCOMPtr<nsIRunnable> trackedRunnable;
       {
         TestCopyWithDeletedMove tracker(&copyCounter);
-        trackedRunnable =
-            aNamed ? NS_NewRunnableFunction("unused", tracker)
-                   : NS_NewRunnableFunction("TestNewRunnableFunction", tracker);
+        trackedRunnable = aNamed ? RunnableFactory::Create("unused", tracker)
+                                 : RunnableFactory::Create(
+                                       "TestNewRunnableFunction", tracker);
       }
       trackedRunnable->Run();
     }
     Expect(
-        "NS_NewRunnableFunction with copyable-only (and deleted move) "
+        "RunnableFactory with copyable-only (and deleted move) "
         "function, copies",
         copyCounter, 1);
   }
 
-  // Test NS_NewRunnableFunction with movable-only function object.
+  // Test RunnableFactory with movable-only function object.
   {
     int moveCounter = 0;
     {
@@ -265,14 +290,13 @@ static void TestNewRunnableFunction(bool aNamed) {
       {
         TestMove tracker(&moveCounter);
         trackedRunnable =
-            aNamed ? NS_NewRunnableFunction("unused", std::move(tracker))
-                   : NS_NewRunnableFunction("TestNewRunnableFunction",
+            aNamed ? RunnableFactory::Create("unused", std::move(tracker))
+                   : RunnableFactory::Create("TestNewRunnableFunction",
                                              std::move(tracker));
       }
       trackedRunnable->Run();
     }
-    Expect("NS_NewRunnableFunction with movable-only function, moves",
-           moveCounter, 1);
+    Expect("RunnableFactory with movable-only function, moves", moveCounter, 1);
   }
   {
     int moveCounter = 0;
@@ -280,17 +304,17 @@ static void TestNewRunnableFunction(bool aNamed) {
       nsCOMPtr<nsIRunnable> trackedRunnable;
       {
         trackedRunnable =
-            aNamed ? NS_NewRunnableFunction("unused", TestMove(&moveCounter))
-                   : NS_NewRunnableFunction("TestNewRunnableFunction",
+            aNamed ? RunnableFactory::Create("unused", TestMove(&moveCounter))
+                   : RunnableFactory::Create("TestNewRunnableFunction",
                                              TestMove(&moveCounter));
       }
       trackedRunnable->Run();
     }
-    Expect("NS_NewRunnableFunction with movable-only function rvalue, moves",
+    Expect("RunnableFactory with movable-only function rvalue, moves",
            moveCounter, 1);
   }
 
-  // Test NS_NewRunnableFunction with copyable&movable function object.
+  // Test RunnableFactory with copyable&movable function object.
   {
     int copyCounter = 0;
     int moveCounter = 0;
@@ -299,16 +323,16 @@ static void TestNewRunnableFunction(bool aNamed) {
       {
         TestCopyMove tracker(&copyCounter, &moveCounter);
         trackedRunnable =
-            aNamed ? NS_NewRunnableFunction("unused", std::move(tracker))
-                   : NS_NewRunnableFunction("TestNewRunnableFunction",
+            aNamed ? RunnableFactory::Create("unused", std::move(tracker))
+                   : RunnableFactory::Create("TestNewRunnableFunction",
                                              std::move(tracker));
       }
       trackedRunnable->Run();
     }
-    Expect("NS_NewRunnableFunction with copyable&movable function, copies",
+    Expect("RunnableFactory with copyable&movable function, copies",
            copyCounter, 0);
-    Expect("NS_NewRunnableFunction with copyable&movable function, moves",
-           moveCounter, 1);
+    Expect("RunnableFactory with copyable&movable function, moves", moveCounter,
+           1);
   }
   {
     int copyCounter = 0;
@@ -317,23 +341,21 @@ static void TestNewRunnableFunction(bool aNamed) {
       nsCOMPtr<nsIRunnable> trackedRunnable;
       {
         trackedRunnable =
-            aNamed ? NS_NewRunnableFunction(
+            aNamed ? RunnableFactory::Create(
                          "unused", TestCopyMove(&copyCounter, &moveCounter))
-                   : NS_NewRunnableFunction(
+                   : RunnableFactory::Create(
                          "TestNewRunnableFunction",
                          TestCopyMove(&copyCounter, &moveCounter));
       }
       trackedRunnable->Run();
     }
-    Expect(
-        "NS_NewRunnableFunction with copyable&movable function rvalue, copies",
+    Expect("RunnableFactory with copyable&movable function rvalue, copies",
            copyCounter, 0);
-    Expect(
-        "NS_NewRunnableFunction with copyable&movable function rvalue, moves",
+    Expect("RunnableFactory with copyable&movable function rvalue, moves",
            moveCounter, 1);
   }
 
-  // Test NS_NewRunnableFunction with copyable-only lambda capture.
+  // Test RunnableFactory with copyable-only lambda capture.
   {
     int copyCounter = 0;
     {
@@ -342,15 +364,16 @@ static void TestNewRunnableFunction(bool aNamed) {
         TestCopyWithNoMove tracker(&copyCounter);
         // Expect 2 copies (here -> local lambda -> runnable lambda).
         trackedRunnable =
-            aNamed ? NS_NewRunnableFunction("unused",
+            aNamed
+                ? RunnableFactory::Create("unused",
                                           [tracker]() mutable { tracker(); })
-                   : NS_NewRunnableFunction("TestNewRunnableFunction",
+                : RunnableFactory::Create("TestNewRunnableFunction",
                                           [tracker]() mutable { tracker(); });
       }
       trackedRunnable->Run();
     }
     Expect(
-        "NS_NewRunnableFunction with copyable-only (and no move) capture, "
+        "RunnableFactory with copyable-only (and no move) capture, "
         "copies",
         copyCounter, 2);
   }
@@ -362,15 +385,16 @@ static void TestNewRunnableFunction(bool aNamed) {
         TestCopyWithDeletedMove tracker(&copyCounter);
         // Expect 2 copies (here -> local lambda -> runnable lambda).
         trackedRunnable =
-            aNamed ? NS_NewRunnableFunction("unused",
+            aNamed
+                ? RunnableFactory::Create("unused",
                                           [tracker]() mutable { tracker(); })
-                   : NS_NewRunnableFunction("TestNewRunnableFunction",
+                : RunnableFactory::Create("TestNewRunnableFunction",
                                           [tracker]() mutable { tracker(); });
       }
       trackedRunnable->Run();
     }
     Expect(
-        "NS_NewRunnableFunction with copyable-only (and deleted move) capture, "
+        "RunnableFactory with copyable-only (and deleted move) capture, "
         "copies",
         copyCounter, 2);
   }
@@ -378,7 +402,7 @@ static void TestNewRunnableFunction(bool aNamed) {
   // Note: Not possible to use move-only captures.
   // (Until we can use C++14 generalized lambda captures)
 
-  // Test NS_NewRunnableFunction with copyable&movable lambda capture.
+  // Test RunnableFactory with copyable&movable lambda capture.
   {
     int copyCounter = 0;
     int moveCounter = 0;
@@ -387,29 +411,30 @@ static void TestNewRunnableFunction(bool aNamed) {
       {
         TestCopyMove tracker(&copyCounter, &moveCounter);
         trackedRunnable =
-            aNamed ? NS_NewRunnableFunction("unused",
+            aNamed
+                ? RunnableFactory::Create("unused",
                                           [tracker]() mutable { tracker(); })
-                   : NS_NewRunnableFunction("TestNewRunnableFunction",
+                : RunnableFactory::Create("TestNewRunnableFunction",
                                           [tracker]() mutable { tracker(); });
         // Expect 1 copy (here -> local lambda) and 1 move (local -> runnable
         // lambda).
       }
       trackedRunnable->Run();
     }
-    Expect("NS_NewRunnableFunction with copyable&movable capture, copies",
-           copyCounter, 1);
-    Expect("NS_NewRunnableFunction with copyable&movable capture, moves",
-           moveCounter, 1);
+    Expect("RunnableFactory with copyable&movable capture, copies", copyCounter,
+           1);
+    Expect("RunnableFactory with copyable&movable capture, moves", moveCounter,
+           1);
   }
 }
 
 TEST(ThreadUtils, NewRunnableFunction)
-{ TestNewRunnableFunction(/*aNamed*/ false); }
+{ TestRunnableFactory<BasicRunnableFactory>(/*aNamed*/ false); }
 
 TEST(ThreadUtils, NewNamedRunnableFunction)
 {
   // The named overload shall behave identical to the non-named counterpart.
-  TestNewRunnableFunction(/*aNamed*/ true);
+  TestRunnableFactory<BasicRunnableFactory>(/*aNamed*/ true);
 
   // Test naming.
   {
@@ -420,6 +445,38 @@ TEST(ThreadUtils, NewNamedRunnableFunction)
   }
 }
 
+TEST(ThreadUtils, NewCancelableRunnableFunction)
+{ TestRunnableFactory<CancelableRunnableFactory>(/*aNamed*/ false); }
+
+TEST(ThreadUtils, NewNamedCancelableRunnableFunction)
+{
+  // The named overload shall behave identical to the non-named counterpart.
+  TestRunnableFactory<CancelableRunnableFactory>(/*aNamed*/ true);
+
+  // Test naming.
+  {
+    const char* expectedName = "NamedRunnable";
+    RefPtr<Runnable> NamedRunnable =
+        NS_NewCancelableRunnableFunction(expectedName, [] {});
+    ExpectRunnableName(NamedRunnable, expectedName);
+  }
+
+  // Test release on cancelation.
+  {
+    auto foo = MakeRefPtr<TestRefCounted>();
+    bool ran = false;
+
+    RefPtr<CancelableRunnable> func =
+        NS_NewCancelableRunnableFunction("unused", [foo, &ran] { ran = true; });
+
+    EXPECT_EQ(foo->refCount(), 2u);
+    func->Cancel();
+
+    EXPECT_EQ(foo->refCount(), 1u);
+    EXPECT_FALSE(ran);
+  }
+}
+
 static void TestNewRunnableMethod(bool aNamed) {
   memset(gRunnableExecuted, false, MAX_TESTS * sizeof(bool));
   // Scope the smart ptrs so that the runnables need to hold on to whatever they

xpcom/threads/nsThreadUtils.h

@@ -659,6 +659,47 @@ already_AddRefed<mozilla::Runnable> NS_NewRunnableFunction(
       aName, std::forward<Function>(aFunction)));
 }
 
+// Creates a new object implementing nsIRunnable and nsICancelableRunnable,
+// which runs a given function on Run and clears the stored function object on a
+// call to `Cancel` (and thus destroys all objects it holds).
+template <typename Function>
+already_AddRefed<mozilla::CancelableRunnable> NS_NewCancelableRunnableFunction(
+    const char* aName, Function&& aFunc) {
+  class FuncCancelableRunnable final : public mozilla::CancelableRunnable {
+   public:
+    static_assert(std::is_void_v<decltype(
+                      std::declval<std::remove_reference_t<Function>>()())>);
+
+    NS_INLINE_DECL_REFCOUNTING_INHERITED(FuncCancelableRunnable,
+                                         CancelableRunnable)
+
+    explicit FuncCancelableRunnable(const char* aName, Function&& aFunc)
+        : CancelableRunnable{aName},
+          mFunc{mozilla::Some(std::forward<Function>(aFunc))} {}
+
+    NS_IMETHOD Run() override {
+      MOZ_ASSERT(mFunc);
+
+      (*mFunc)();
+
+      return NS_OK;
+    }
+
+    nsresult Cancel() override {
+      mFunc.reset();
+      return NS_OK;
+    }
+
+   private:
+    ~FuncCancelableRunnable() = default;
+
+    mozilla::Maybe<std::remove_reference_t<Function>> mFunc;
+  };
+
+  return mozilla::MakeAndAddRef<FuncCancelableRunnable>(
+      aName, std::forward<Function>(aFunc));
+}
+
 namespace mozilla {
 namespace detail {